Q: You created the first widely successful NoSQL document database. What did you base that architecture on?

A: It wasn't based on anything in particular; it's a career's worth of learning what works and what doesn't. We were looking at cloud computing -- at needs for horizontal scalability and how we wanted to write code -- and we couldn't find tools that did what we wanted. There are a couple of dimensions in which things are very difficult. One is: Just how do you scale out? There are a couple aspects of scale that are superhard theoretically, and one of them is distributive joins. If you want to do distributive joins on a 1,000-server cluster, that's a hard problem.

Our point of view on that was to say: Well, I don't have a clever way to do distributive joins, so instead, we're not going to do them. We're going to try to pick a data model that allows us to create something that's very useful without having them. That kind of levels into the document-oriented data model, which we like a lot anyway for development purposes. We thought it was a really good fit in terms of the way people code today.

That was sort of like the catalyst that kind of got us going in this direction. I think if you look at the NoSQL space -- next-generation, horizontally scalable, nonrelational databases -- they basically all have those properties. I really like document orientation as a concept, because it fits well with the way we write code. iI's pretty readable, especially for developers and DBAs. One of the big ideas in databases is separating the data from the code. I should be able to look at the contents of the database without hurting the program. I think that's maintained here, and I think relational did that well too.

I also like JSON (JavaScript object notation) a lot as a basis for documents. JSON gives us a standards-based, independent language for object-style data, and I find it easier to read as a human than, say, XML. Several of the NoSQL products are JSON-style, document-oriented databases. I think that's really kind of the sweet spot there in terms of the data model that's going to be somewhat standardized in that space.

Q: Why make MongoDB open source? Did you have a business model in mind from the very start?

A: I think it was for several reasons. One is we like open source conceptually, as developers. We're just fans of it. We think it makes a lot of sense. But in addition, we think you can build great businesses in the open source world that are complementary to the free project. Red Hat is a great company and a pretty big company.

Q: Who were your first customers?

A: Our first customers were from the Web 2.0 and startup world. That was kind of back in 2009, so you have folks like Shutterfly or Craigslist or Foursquare using MongoDB. Then a year later we saw bigger enterprises using the product, folks like a Intellisponse or O2 or Disney or eBay. And now even at the enterprise level we're getting beyond the early-adopter phase. In 2012 the biggest trend I saw in terms of adoption was financial services, where banks and other financial firms were adopting MongoDB and NoSQL in general quite widely. They use it for new projects. They have all this legacy stuff, of course, but the majority of them are now NoSQL for at least some percentage of their new projects. There are some organizations who are saying: This is our default way to build apps.